More than 3 million more people lacked health insurance at the end of 2017 relative to the end of 2016, according to the Gallup-Sharecare Well-Being Index. A recent estimate of the connection between a lack of insurance and mortality suggests that for every 800 people without insurance for a year, one will die — meaning that 4,000 more people may have died during the year than would have had they been covered.

That increase in the percentage began in the first quarter of Donald Trump’s presidency. In the fourth quarter of 2016, the percentage of uninsured adults in the United States was 10.9 percent — a low after three years of declines following the passage of the Affordable Care Act (better known as Obamacare). In 2013, before the law went into effect, nearly 1 in 5 adults lacked insurance. Over the course of last year, that figure rose again to 12.2 percent.

The largest driver for this change, Gallup reports, was people declining to buy their own insurance. Over the course of 2017, as Republicans on Capitol Hill debated the shape of a possible repeal of the ACA, the mandate that individuals have health-care coverage was a frequent target of rhetoric. In December, as part of the sweeping tax-overhaul bill signed into law by Trump, that mandate was repealed. An analysis of the effects of that measure by the nonpartisan Congressional Budget Office in November found that the repeal would lead to 13 million fewer people with insurance coverage by 2027 — and 4 million more by 2019.

According to the aforementioned assessment of mortality among the uninsured — an assessment which reflects the middle of a range of estimates — that could mean 16,250 more deaths a year.

Gallup’s survey, though, suggests that the drop in coverage is, so far, not evenly distributed. Since those over the age of 65 have access to Medicare, the percentage of uninsured in that group actually fell from 2.3 percent to 2.1 percent between the last quarter in 2016 and the last quarter of 2017. In every other age group, the percentage of uninsured went up, with the biggest increase among those 25 and under.

Poorer Americans and nonwhites also saw bigger increases in the percentage that lack insurance coverage. Among those earning under $36,000 a year, the percent without insurance jumped from 20.8 to 22.8 percent — despite the ACA providing subsidies for coverage to people in that income range. Among black Americans, the rate jumped from 12.5 to 14.8 percent — and among Hispanics, the percentage of uninsured is now nearly 30 percent.

Obamacare had been narrowing the gap between whites and nonwhites on health coverage. At the end of 2013, 20.9 percent of black Americans and 38.7 percent of Hispanics were uninsured, compared with 11.9 percent of whites. That’s a difference of 9 and 26.8 points respectively. At the end of 2016, the rate among blacks was 5.6 points higher than among whites, and the rate among Hispanics was 20.5 points higher. Now, those margins are back to 7.2 and 22 points.

Those gaps will likely widen further. In part, this is a function of the CBO’s projection that the number of uninsured Americans will continue to increase. In part, too, it’s a function of shifts in how the government promotes the law. In 2017, the Trump administration scaled back outreach efforts to promote enrollment in Obamacare, a shift that was seen by many — including some in Congress — as likely resulting in drops in enrollment among nonwhite populations.

It’s hard to know precisely how this will affect the populations who no longer have health-care coverage. The mortality rate estimate is just that, an estimate based on evidence from analysis of coverage changes. (For obvious reasons, there are not direct experiments in which people are asked not to get health-care coverage to see if they live.) The expansion of health-care coverage under Obamacare also had an economic effect, with the number of bankruptcies nationally dropping by 50 percent from 2010 to 2016 (not all of which was a function of the health-care law). Those without insurance coverage who suddenly find themselves with large health-care bills may increasingly be forced to declare bankruptcy.

It was one year ago Sunday that Trump pledged his administration would provide “insurance for everybody.”